Field of the Invention
Embodiments disclosed herein relate generally to methods and systems for treating water to change the properties thereof, including rheological, flocculation, and flow properties. More specifically, embodiments disclosed herein relate generally to methods and systems for reducing drag/improving flow of water in water injection systems for hydrocarbon recovery.
Background Art
Hydrocarbons accumulated within a subterranean hydrocarbon-bearing formation are recovered or produced therefrom through production wells drilled into the subterranean formation. Initially, oil is produced from a formation by pressure depletion. In this method, the differential pressure between the formation and a production well or wells forces the oil contained within the formation toward a production well where it can be recovered. Typically, only about 10 to about 35 percent of the oil which is contained within a formation can be recovered from a formation using pressure depletion. Additionally, some formations contain oil which is too viscous to be efficiently recovered from the formation using pressure depletion methods. Because of the need to recover a larger percentage of the original oil-in-place from a formation, several methods have been developed which facilitate the recovery of oil which could not be recovered using pressure depletion techniques. These methods are sometimes hereinafter referred to as “oil recovery techniques.”
When production of hydrocarbons slows, one or more injection wells may be drilled into the formation, into which fluid may be injected to maintain reservoir pressures and serve as a driving mechanism for the flow of hydrocarbons through the formation so that they may be produced from production well(s). One type of such recovery operation uses a water source, such as fresh water, brines, sea water, or produced/formation water, etc., as the injection fluid to maintain reservoir pressure and thus maintain or boost production levels.
Further, the injected water may create a vertical flood front, pushing the oil in front of the water front toward the producing well, which is referred to as water flooding. The injected water moves within the formation and mobilizes the accumulations of oil contained therein. The mobilized oil is moved within the formation toward a production well or wells where it is recovered. Water flooding may be used alone, or it may be combined with other techniques which are performed concurrently with the water flood or subsequent to it. Fluids injected later can be referred to as driving fluids. Although water is the most common, other injection and drive fluids can include gaseous fluids such as steam, carbon dioxide, and the like.
In addition, as reservoirs mature, the amount of produced water increases. To allow for environmentally friendly, and economically efficient, disposal of the produced water frequently occurs by reinjection of the produced water into the producing reservoir or injection into an abandoned reservoir.
The injection of water, however, is often limited by pumping capacity on the platform or well site, the capacity of the injection tubing or pipelines, and the reservoir. In particular, turbulent flow through the pipes presents even greater limitations on the pumping capacity and the energy expelled for injecting water into a producing reservoir (or abandoned reservoir for disposal).
Accordingly, there exists a continuing need for improvements in methods and systems for water injection into reservoirs.